DESCRIPTION: (Applicant's Abstract) This multidisciplinary research project by four principal investigators seeks to develop a comprehensive approach for the systematic development of conformationally and topographically constrained analogues of dynorphin that have high potency at, and selectivity for, the opioid receptor and its subtypes, high stability in vivo, potent agonist and antagonist biological activities, and prolonged biological effects. This research requires the broad utilization of a wide variety of chemical and biological approaches, including computer aided drug design, asymmetric synthetic organic chemistry and synthetic peptide chemistry, conformational analysis using state-of-the-art biophysical methods including 2D-NMR in conjunction with molecular mechanics and molecular dynamics calculations, and in vitro and in vivo pharmacological, biochemical and physiological studies including use of the cloned human kappa opioid receptor(s). The specific aims of this research include: 1) the design of conformationally and topographically constrained dynorphin analogues that are potent and selective for the opioid receptor; 2) the design, synthesis and utilization of topographically fixed or biased amino acids and amino acid mimetics to obtain receptor selective ligands; 3) careful evaluation of the newly synthesized bioactive compounds in kappa, mu and delta binding assays using guinea pig brain homogenates and the cloned kappa receptor, including a search for kappa receptor subtypes; 4) full evaluation of in vitro bioactivities using the guinea pig ileum and mouse vas deferens bioassays, and evaluation of new analogue efficacies in this assay and in transfected cells with kappa receptors; 5) careful evaluation of the new stability of the analogues against biodegradation; 6) careful evaluation of the conformational properties of our best leads to determine the pharmacophore (biologically active conformation) for dynorphins at kappa opioid receptors. The long term goal is to develop kappa receptor ligands for the treatment of pain and disease.